[Always *]

Bare in mind that I'm not a medical professional so I can't be the one to say for sure, but I would be happy to share my own insight to what you described to hopefully help you out (mini disclaimer is done now lol)

For the loss of appetite - You mention that you have depression, and I know that that can affect your health. I have anxiety and I know that I've also felt that way where I just don't feel hungry (even though I am hungry?). It's a side affect / symptom of many mood disorders to lose your appetite (anxiety and depression being the more common ones).

For eating the sugar, I mean, we all have quirks? It might just be the funny little thing that is your response / coping mechanism. I'm not quite sure why your specifically eating what I understand is white sugar - is there a lack of other sugary foods in your home? - but who knows.

If this is something your struggling with, you could try counselling. Talking to a professional can help a lot to work through these things and identify why you think and act the way you do (trust me, it helps).